We propose to continue studying morphologic and functional aspects of the juxtaglomerular (JG) complex that are still inadequately explained or resolved by presently existing evidence. Our aim is to contribute to a better understanding of mechanisms of diseases associated with secondary aldosteronism, hypertension, anemia and polcythemia. Specific problems and proposed approaches are as follows. The relation between the renin-angiotensin and renal erythropoietic (REF) - erythropoietin (ESF) systems will be studied in animals with acute and chronic anemia that are fed diets with low, normal and high sodium contents. Techniques will include bioassay, light and electron microscopy, and tissue localization of renin and REF by immunochemistry. Morphology of the glomerular vascular pole will be done in in vitro systems designed to elucidate factors causing renin release by JG cells. To test the influence of the sympathetic nervous system on morphology and function of JG cells, newborn animals will be treated with Guanethidine. Transplants of renal medulla in hypertensive rats will be examined by standard microscopic techniques in an effort to help understand the function of interstitial cells and the effect of these cells on the JG complex.